Validate and encode query parameters

sdk/azcore/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Features Added
 
+* Added function `FetcherForNextLink` to the `runtime` package to centralize creation of `Pager[T].Fetcher` from a next link URL.
+
 ### Breaking Changes
 
 ### Bugs Fixed

sdk/azcore/runtime/pager.go

@@ -11,8 +11,10 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"net/http"
 	"reflect"
 
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/tracing"
 )
 
@@ -88,3 +90,25 @@ func (p *Pager[T]) NextPage(ctx context.Context) (T, error) {
 func (p *Pager[T]) UnmarshalJSON(data []byte) error {
 	return json.Unmarshal(data, &p.current)
 }
+
+// FetcherForNextLink is a helper containing boilerplate code to simplify creating a PagingHandler[T].Fetcher from a next link URL.
+func FetcherForNextLink(ctx context.Context, pl Pipeline, nextLink string, createReq func(context.Context) (*policy.Request, error)) (*http.Response, error) {
+	var req *policy.Request
+	var err error
+	if nextLink == "" {
+		req, err = createReq(ctx)
+	} else if nextLink, err = EncodeQueryParams(nextLink); err == nil {
+		req, err = NewRequest(ctx, http.MethodGet, nextLink)
+	}
+	if err != nil {
+		return nil, err
+	}
+	resp, err := pl.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if !HasStatusCode(resp, http.StatusOK) {
+		return nil, NewResponseError(resp)
+	}
+	return resp, nil
+}

sdk/azcore/runtime/pager_test.go

@@ -14,6 +14,7 @@ import (
 	"testing"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/internal/exported"
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
 	"github.com/Azure/azure-sdk-for-go/sdk/internal/mock"
 	"github.com/stretchr/testify/require"
 )
@@ -256,3 +257,59 @@ func TestPagerResponderError(t *testing.T) {
 	require.Error(t, err)
 	require.Empty(t, page)
 }
+
+func TestFetcherForNextLink(t *testing.T) {
+	srv, close := mock.NewServer()
+	defer close()
+	pl := exported.NewPipeline(srv)
+
+	srv.AppendResponse()
+	createReqCalled := false
+	resp, err := FetcherForNextLink(context.Background(), pl, "", func(ctx context.Context) (*policy.Request, error) {
+		createReqCalled = true
+		return NewRequest(ctx, http.MethodGet, srv.URL())
+	})
+	require.NoError(t, err)
+	require.True(t, createReqCalled)
+	require.NotNil(t, resp)
+	require.EqualValues(t, http.StatusOK, resp.StatusCode)
+
+	srv.AppendResponse()
+	createReqCalled = false
+	resp, err = FetcherForNextLink(context.Background(), pl, srv.URL(), func(ctx context.Context) (*policy.Request, error) {
+		createReqCalled = true
+		return NewRequest(ctx, http.MethodGet, srv.URL())
+	})
+	require.NoError(t, err)
+	require.False(t, createReqCalled)
+	require.NotNil(t, resp)
+	require.EqualValues(t, http.StatusOK, resp.StatusCode)
+
+	resp, err = FetcherForNextLink(context.Background(), pl, "", func(ctx context.Context) (*policy.Request, error) {
+		return nil, errors.New("failed")
+	})
+	require.Error(t, err)
+	require.Nil(t, resp)
+
+	srv.AppendError(errors.New("failed"))
+	resp, err = FetcherForNextLink(context.Background(), pl, "", func(ctx context.Context) (*policy.Request, error) {
+		createReqCalled = true
+		return NewRequest(ctx, http.MethodGet, srv.URL())
+	})
+	require.Error(t, err)
+	require.True(t, createReqCalled)
+	require.Nil(t, resp)
+
+	srv.AppendResponse(mock.WithStatusCode(http.StatusBadRequest), mock.WithBody([]byte(`{ "error": { "code": "InvalidResource", "message": "doesn't exist" } }`)))
+	createReqCalled = false
+	resp, err = FetcherForNextLink(context.Background(), pl, srv.URL(), func(ctx context.Context) (*policy.Request, error) {
+		createReqCalled = true
+		return NewRequest(ctx, http.MethodGet, srv.URL())
+	})
+	require.Error(t, err)
+	var respErr *exported.ResponseError
+	require.ErrorAs(t, err, &respErr)
+	require.EqualValues(t, "InvalidResource", respErr.ErrorCode)
+	require.False(t, createReqCalled)
+	require.Nil(t, resp)
+}

sdk/azcore/runtime/request.go

@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"io"
 	"mime/multipart"
+	"net/url"
 	"os"
 	"path"
 	"reflect"
@@ -43,6 +44,19 @@ func NewRequest(ctx context.Context, httpMethod string, endpoint string) (*polic
 	return exported.NewRequest(ctx, httpMethod, endpoint)
 }
 
+// EncodeQueryParams will parse and encode any query parameters in the specified URL.
+func EncodeQueryParams(u string) (string, error) {
+	before, after, found := strings.Cut(u, "?")
+	if !found {
+		return u, nil
+	}
+	qp, err := url.ParseQuery(after)
+	if err != nil {
+		return "", err
+	}
+	return before + "?" + qp.Encode(), nil
+}
+
 // JoinPaths concatenates multiple URL path segments into one path,
 // inserting path separation characters as required. JoinPaths will preserve
 // query parameters in the root path

sdk/azcore/runtime/request_test.go

@@ -740,3 +740,22 @@ func TestSetMultipartFormData(t *testing.T) {
 	require.Equal(t, "second part", string(second))
 	require.Equal(t, "third part", string(third))
 }
+
+func TestEncodeQueryParams(t *testing.T) {
+	const testURL = "https://contoso.com/"
+	nextLink, err := EncodeQueryParams(testURL + "query?$skip=5&$filter='foo eq bar'")
+	require.NoError(t, err)
+	require.EqualValues(t, testURL+"query?%24filter=%27foo+eq+bar%27&%24skip=5", nextLink)
+	nextLink, err = EncodeQueryParams(testURL + "query?%24filter=%27foo+eq+bar%27&%24skip=5")
+	require.NoError(t, err)
+	require.EqualValues(t, testURL+"query?%24filter=%27foo+eq+bar%27&%24skip=5", nextLink)
+	nextLink, err = EncodeQueryParams(testURL + "query?foo=bar&one=two")
+	require.NoError(t, err)
+	require.EqualValues(t, testURL+"query?foo=bar&one=two", nextLink)
+	nextLink, err = EncodeQueryParams(testURL)
+	require.NoError(t, err)
+	require.EqualValues(t, testURL, nextLink)
+	nextLink, err = EncodeQueryParams(testURL + "query?invalid=;semicolon")
+	require.Error(t, err)
+	require.Empty(t, nextLink)
+}